The present disclosure relates generally to friction stir riveting and a method of joining therewith, and particularly to a friction stir rivet and method that has a reduced tendency to undesirably displace softened friction stirred material sideways into the joint between the workpieces being joined.
Friction stir welding (FSW) is a method used to join metal workpieces that generally uses a cylindrical shouldered tool with a profiled pin that is rotated at the joint line between two workpieces while being traversed along the joint line. The rotary motion of the tool generates frictional heat that serves to soften and plasticize the workpieces. As the pin moves laterally, the softened material, contributed by both workpieces, intermingles in the wake of the traversing pin and cools and hardens due to the absence of further frictional stirring, creating a bond between the two workpieces.
Recent advances in friction stir processes have extended the FSW technique to friction stir riveting (FSR), where a stir rivet is rotated and advanced into an arrangement of workpieces to be joined such that the material of the workpieces plasticizes around the rivet during the friction stirring, and then hardens around the rivet when the body of the rivet stops rotating and the workpieces and rivet are allowed to cool.
While present devices and methods may be suitable for their intended purposes, it is desirable to further advance the technology of friction stir riveting in a manner that offers opportunities for joining dissimilar materials.